As a transparent conductive film used in a touch panel, there is a film having, on one surface thereof, a transparent wiring layer formed by patterning a transparent conductive membrane.
In recent years, in a touch panel mounted onto a smart phone and the like, optical properties thereof have been improved. In other words, it has been required to keep color tones of images viewed through the touch panel, and to make the presence of its transparent wiring layer inconspicuous. Additionally, it is also required to make the transparent wiring layer finer in line width, and to have a high durability.
As a technique of ensuring the transparency of the transparent wiring layer to make the wiring inconspicuous, for example, a transparent conductive film having an optical adjustment layer formed between a substrate film and a transparent conductive membrane (transparent wiring layer) is suggested (Patent Documents 1 and 2).
As the transparent wiring layer, ITO (indium tin oxide) is used. From the viewpoint of the durability and optical properties of the transparent wiring layer, crystalline ITO is used.